GB742992A - Improvements in crane construction - Google Patents

Abstract

742,992. Jib cranes ; preventing load from swinging. COLBY STEEL & MANUFACTURING, Inc. Nov. 25, 1952, No. 29843/52. Class 78 (4). A slueing jib crane has two hoist cables 75, 81, Fig. 13, which pass each over one of a pair of spaced pulleys 80, 86 at the end of the jib to winding apparatus which includes differential means permitting the length of the cables 75, 81 to vary in opposite senses as the load swings. The cables 75, 81 are secured to a spreader 87 and after passing over the pulleys 80, 86, which are pivoted to form fairleads, pass over laterally spaced pulleys 79, 85, Figs. 1 and 12, and are reeved around pairs of pulleys 78 and 84, 77 and 83, 76 and 82 before passing to a pair of hoist drums 53, 54, Fig. 3. The drums 53, 54 are driven from a shaft 52 through a differential gear mounted between the drums and are controlled by selectively operable brake bands 61, 62. The pulleys 79 and 85, 77 and 83, 78 and 84, 76 and 82 are so disposed that the load hook 88 moves horizontally when the jib 19 is luffed. A further cable 116 is secured to the spreader 87 and passes over pulleys 117 on the jib to a drum 118 which is controlled by a torsion spring or by a constant torque motor and which may be braked. The jib is luffed by cables 42, 44 secured at 43, 45 to widely spaced points on the jib and reeved around pairs of pulleys 26 and 29, 23 and 24, 27 and 28 before passing to a pair of integral winding drums 34, 35 provided with a brake 41. While swinging of the load is preferably controlled by the brakes 61, 62 it may be partially damped by friction in the pulleys over which the hoist cables pass. In the alternative arrangement of Fig. 14 the drums 53, 54 of Fig. 3 are directly connected and the differential movement of the hoist cables is provided by mounting the pulleys 77, 83 to slide in brackets 120 and connecting them by a lever 126 pivoted at 127. Swinging of the load is then damped by a pair of pistons 129 and cylinders 130 connected to the ends of the levers 126 and controlled by manuallyoperated valves in a conduit joining them. The upper slueing parts 12, 14, Fig. 12, of the crane are supported from a column 11 by a thrust bearing (not shown) at the upper end of the pillar 14 and are further guided by rollers 15, Fig. 4, engaging the column 11. The crane is slued by a pinion 17, Fig. 4, mounted on the slueing part of the crane and engaging internal or external teeth on a fixed ring 16. Hydraulic motors 67, Fig. 4, 46 and 30, Fig. 3, provide respectively the slueing, hoisting and luffing motions. They are driven from rotary pumps 65, 66, 74 driven from an electric motor 63 and controlled by members 109, 115, 105. The member 115 controlling hoisting is connected by a cable 114, Fig. 11, to a pivoted lever 97 and the member 109 controlling slueing is connected by a cable 108, Fig. 10, to a universally mounted lever 98. The cable 108 passes through an arcuate slit in the lower end of the lever 98 and is coupled by buttons 110 to the lever. Movement of the lever 98 in a direction at right angles to that controlling slueing turns a pair of arms 103 which are connected by a cable 104 to operate the member 105 controlling luffing. A pedal controls the luffing brake 41 and pair of pedals set side-by-side so that they can be operated by one foot control the hoisting brakes 61, 62. The hydraulic motor 67 for slueing may be replaced by a motor which provides a gradual stop.